1month in India itinerary help

Hello everyone,

I am planning to visit india, and with 30 days visa; I will most likely start in New Delhi, and to the famous golden-triangle route as a start.

I am also into nature/hiking/off-the-path, any recommendation?

My current plan / tentative plan is

1. finish golden triangle

2. spend some time in the south (Goa, Mumbai), and explore nearby areas.

Any others recommendations / sightseeing / adventures I should look into will be highly appreciative!